(a) Field of the Invention
The present invention relates to a hobnail structure, and more particularly to a hobnail structure that can be screwed to a hole seat at sole of a sports shoe, so as to enhance a tight assembling of the hobnail and sole.
(b) Description of the Prior Art
As a promotion of sport quality, all kinds of sports shoes are designed according to requirements of characteristics of each kind of sport. For example, soccer is a kind of world-wide sport wherein fast movements and instant stand-stills are required for a player during offense or defense. Therefore, a plurality of hobnails is installed on the soles of sports shoes to enhance their grip. However, to facilitate a replacement and maintenance of hobnails, the hobnail structures are provided with threads that can be screwed to the hole seats.
Referring to FIG. 1, for a conventional hobnail structure, a plurality of hole seats 60 is specifically located at pre-determined positions on a sole, and each hole seat is screwed with a hobnail 61 which is provided with a bolt 62 having external threads. A ring 63 of a larger diameter is located at one end of the bolt, and a plurality of grooves 64 is located radially at rims of the ring. The exterior of the grooves is compulsively latched with a cap 65, the lower end of which is latched with a decorative ring 66 at the same time. By way of screwing the bolt 62 to the hole seat, the hobnail can be conveniently replaced and maintained. However, upon screwing the conventional hobnail to the sole, it is often that the bolt 62 will be continuously shifted downward due to a function of the threads, such that the cap 65 is pushed against an end surface of the hole seat to form an reaction force when the decorative ring 66 is locked into an extremity, resulting from an excessive exertion of a rotation force with an auxiliary wrench. As the grooves 64 are located radially, it is very easy for the cap 65 to displace outward along a shifting of the radial grooves of the ring, and a gap will be created (as shown in FIG. 2) due to that the bolt 62 is moving in a direction opposite to that of the cap 65. In addition, it is easy to create a strip phenomenon, such that the cap will detach from the ring and be damaged, which is imperfect.
In view of the disadvantages existent in the prior art, the inventor has researched to improve the hobnail structure and experienced a number of tests. Accordingly, a hobnail structure that can be tightly locked and firmly fixed has been invented.